The present invention relates to apparatus for dispensing liquid soap, normally in discrete small quantities or charges. The invention has particular application to the dispensing of liquid soap from replaceable cartridges which may contain grit for scouring purposes.
One type of soap dispenser is disclosed in U.S. Pat. No. 4,108,363 and includes a flexible pump bowl which receives soap from a container through a diaphragm-type check valve. When the bowl is compressed it closes the check valve and forces the soap in the bowl out through a passageway to a discharge outlet. This structure is relatively complex and is not well suited to modern distribution networks which require field maintenance by unskilled laborers, nor is it suited to the dispensing of soap containing grit, since the grit tends to clog the passageways in the device thereby increasing maintenance problems.
A similar type of dispenser using a compressible pump bowl or nipple is disclosed in U.S. Pat. No. 1,326,880, the dispenser ejecting soap directly from a slit in the pump nipple. This dispenser utilizes a custom-made check valve stopper in the soap container outlet, and depends on distortion of the slit in the nipple for dispensing of soap therefrom. Thus, the nipple is compressed in the direction of the slit. This has the disadvantage that the slit can be opened permitting soap to drip therefrom before pressure in the nipple has been raised sufficiently to close the check valve.
Another type of soap dispenser is disclosed in the Cassia EPC application Ser. No. 86300742.3, published Aug. 18, 1987, under publication no. 023 571, which includes mechanisms for dispensing discrete quantities of liquid soap. A problem which has been encountered in most of the prior art soap dispensing devices including those devices to Cassia is that repeated discharges of the dispensing mechanism of the soap results in less than full quantities of soap being discharged after the initial operation. Basically this is because there is insufficient air bleed to the soap container or cartridge so that refill into the discharge nozzle or nipple is not sufficient so that the prior art has not solved the problem of providing a full dosage when soap dispensers of the type referenced are subjected to repeated rapid uses, as is common in public washrooms and the like.